U.S. patent number 6,705,642 [Application Number 10/049,929] was granted by the patent office on 2004-03-16 for device for controlled deflation of a gas bag.
This patent grant is currently assigned to Daimlerchrysler AG, I.E.E. International Electronics & Engineering S.a r.l.. Invention is credited to Ernst Johann Hauer, Michael Meyer, Volker Petri, Harald Rudolf, Bogdan Serban, Michel Witte.
United States Patent |
6,705,642 |
Serban , et al. |
March 16, 2004 |
Device for controlled deflation of a gas bag
Abstract
A device for deflating a gas bag includes a gas bag having a
deflation opening which is closed along a breakable, predetermined
line. The predetermined breaking line includes a closure element
and is breakable by melting or sublimating the closure element.
Inventors: |
Serban; Bogdan (Niederkorn,
LU), Hauer; Ernst Johann (Steinheim, LU),
Witte; Michel (Luxembourg, LU), Petri; Volker
(Aidlingen, DE), Rudolf; Harald (Tubingen,
DE), Meyer; Michael (Alfdorf, DE) |
Assignee: |
I.E.E. International Electronics
& Engineering S.a r.l. (Luxembourg, LU)
Daimlerchrysler AG (Stuttgart, DE)
|
Family
ID: |
19731828 |
Appl.
No.: |
10/049,929 |
Filed: |
February 20, 2002 |
PCT
Filed: |
August 30, 2000 |
PCT No.: |
PCT/EP00/08460 |
PCT
Pub. No.: |
WO01/15942 |
PCT
Pub. Date: |
March 08, 2001 |
Foreign Application Priority Data
Current U.S.
Class: |
280/739;
280/735 |
Current CPC
Class: |
B60R
21/239 (20130101); B60R 21/01516 (20141001); B60R
21/01528 (20141001); B60R 2021/23576 (20130101) |
Current International
Class: |
B60R
21/16 (20060101); B60R 21/01 (20060101); B60R
021/28 () |
Field of
Search: |
;280/739,734,743.1,731,732,735 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
0 836 971 |
|
Apr 1998 |
|
EP |
|
2 306 409 |
|
May 1997 |
|
GB |
|
WO 00/35719 |
|
Jun 2000 |
|
WO |
|
Other References
Yaniger, S.I.: "Force Sensing Resistors: A Review of the
Technology": Electro International Conference record, US, western
Periodicals Co., Ventura, CA; vol. 16, Apr. 16, 1991, pp. 666-668,
XP000288444..
|
Primary Examiner: Dunn; David R.
Attorney, Agent or Firm: McCormick, Paulding & Huber
LLP
Claims
What is claimed is:
1. A device for deflating a gas bag said gas bag comprising at
least one deflation opening which is closed at a breakable,
predetermined breaking line, wherein said predetermined breaking
line comprises a closure element and wherein said breaking line is
breakable by actively and selectively melting or sublimating said
closure element at any stage of inflation of said gas bag.
2. The device according to claim 1, wherein said predetermined
breaking line comprises a closure seam manufactured according to an
appropriate manufacturing technique in the material of said gas bag
and wherein said closure element comprises a seam fiber
manufactured of said material of said gas bag.
3. The device according to claim 2 wherein an electrical heating
element, in particular an electrically conductive heating fiber, is
associated with said seam fiber, said heating element heating said
seam fiber to a temperature above the melting temperature of said
material of said gas bag at at least one position when an
electrical current is passed through said heating element.
4. The device according to claim 1, wherein said predetermined
breaking line comprises a closure seam and wherein said closure
element comprises a seam fiber made from an electrically conductive
material.
5. The device according to claim 1, wherein said predetermined
breaking line comprises a first and a second row of closure
members, said closure members of said first row being arranged on a
first edge of said deflation opening of said gas bag, and said
closure members of said second row being arranged in such a manner
on a second edge of said deflation opening of said gas bag that
said closure members of said first row and said closure members of
said second row are offset relative to one another in the direction
of said predetermined breaking line, wherein said closure members
of said first row and said closure members of said second row
interlockingly engage in a closed condition of said gas bag and
wherein said closure element comprises an electrically conductive
fiber, which holds together said first and said second row of
closure members at at least one position.
6. The device according to claim 5, wherein said predetermined
breaking line is designed as a slide-less zip fastener, which is
worked into said deflation opening of a gas bag.
7. The device according to claim 5, wherein at least one of said
rows of closure members comprises a gap in such a manner that a
chain formed in said closed condition of said gas bag by said
interlocking closure members is interrupted at one position and
comprises an opening, and wherein said electrically conductive
fiber is arranged for holding together said first and second row of
closure members in the region of this opening.
8. The device according to claim 5, wherein said closure members of
said first row and said closure members of said second row do not
interlock at one position, in such a manner that a chain formed in
said closed condition of said gas bag by said interlocking closure
members is interrupted at this position and comprises an opening,
and wherein said electrically conductive fiber is arranged for
holding together said first and second row of closure members in
the region of this opening.
9. The device according to claim 5, wherein said closure element
encloses said first and second row of closure members.
10. The device according to claim 5, wherein at least some of said
closure members of said first and second row are designed in a loop
shape in such a manner that a chain formed in said closed condition
of said gas bag by said interlocking closure members comprises a
longitudinal channel at one position in the interior of said
loop-shaped closure members running in the direction of said
predetermined breaking line, and wherein said closure element is
inserted at least partially in said longitudinal channel.
11. The device according to claim 5, wherein said melting or
sublimation of said closure element is caused by an electrical
current passing through said closure element.
12. The device according to claim 1, wherein said gas bag is an
airbag.
13. A passenger safety system for a vehicle comprising at least one
airbag, said airbag comprising at least one deflation opening which
is closed at a breakable, predetermined breaking line, wherein said
predetermined breaking line comprises a closure element and wherein
said breaking line is breakable by actively and selectively melting
or sublimating said closure element at any stage of inflation of
said gas bag, a sensor device for detecting the relative position
of said passenger relative to said airbag, and a control device,
said control device controlling the melting or sublimation of said
breaking line on the basis of a position signal determined by said
sensor device at a given position of said passenger relative to
said airbag.
14. The passenger safety system according to claim 13, wherein said
control device comprises means for evaluating said position signal
from said sensor device with reference to pressure.
15. The passenger safety system according to claim 13, wherein said
sensor device comprises at least one sensor, which is arranged on
said airbag in a region which is facing said passenger when said
airbag is released.
16. The passenger safety system according to claim 15, wherein said
sensor is a force sensor arranged on said airbag.
17. The passenger safety system according to claim 16, wherein said
force sensor comprises at least two electrode structures, which are
arranged at a given distance relative to one another on a textile
carrier material and a layer made from a semiconductor material,
which is arranged on said electrode structures in an active region
of said sensor in direct contact with said electrode structures,
wherein said layer of semiconductor material comprises an internal
resistance, which varies in dependence upon the deformation of said
layer.
18. The passenger safety system according to claim 17, wherein said
textile carrier material comprises said airbag material, wherein
said electrode structures are attached directly to said airbag.
19. The passenger safety system according to claim 13, wherein said
control device comprises means for evaluating said position signal
from said sensor device with reference to time.
20. The passenger safety system according to claim 13, wherein said
control device comprises means for evaluating said position signal
from said sensor device with reference to pressure and time.
Description
FIELD OF THE INVENTION
The present invention relates to a device for deflating a gas bag,
in particular for deflating an airbag in an active passenger safety
system in a vehicle.
BACKGROUND OF THE INVENTION
In order to reduce the risk of injury to passengers in a vehicle in
the event of a traffic accident, modern vehicles are increasingly
equipped with an active passenger safety system. An active
passenger safety system of this kind generally comprises one or
more airbags, which are inflated extremely quickly in the event of
an impact of the vehicle, and which absorb the energy released by
the passenger on impact.
The airbag, for example a frontal airbag, is released from the
dashboard respectively the impact cup of the steering wheel at a
very high velocity (200 to 300 km per hour). In order to avoid
injuries to the passenger caused by the release of the airbag it is
therefore advantageous to interrupt or control the complete
inflation or unfolding of the airbag, as soon as the passenger has
plunged sufficiently far into the airbag and an adequate pressure
has built up in the airbag to absorb the energy of the passenger
safely. Because the time at which the passenger has plunged
sufficiently far into the airbag depends very strongly on the
seating position of the passenger at the time of the accident, the
interruption of the inflation procedure of the airbag may become
necessary at any stage of its release.
Since an inflation device which functions on the basis of
pyrotechnology, a so-called inflator, cannot, as a result of the
system, be interrupted at any desired time in its function, a
passenger safety system must consequently comprise a device for
targeted deflation of said airbag in order to control the
interruption of the release procedure of the airbag. A device of
this kind must allow the gas introduced by the inflator into the
airbag to be released at any desired time in order to prevent the
continued inflation of the airbag.
A device is known from WO-A-98/01323, in which the gas bag
comprises a deflation opening, which is closed at a predetermined
breaking line. The breaking line is designed in such a manner that
it remains intact below a predetermined target pressure within the
airbag, and automatically breaks open under the influence of said
pressure above the target pressure. A predetermined breaking line
of this type is generally achieved through a careful, technically
accurately dimensioned weakening of the material used. Such a
weakening of the material can be achieved e.g. by a perforation, in
which small incisions are made along the predetermined breaking
line. In another embodiment, the predetermined breaking line is
produced when closing said airbag by means of a seam produced by
stitching, whereby the thread used for stitching and the spacing
between stitches is adapted accurately to the requirements for the
release of the airbag. Alternatively, the airbag skin may also be
sealed by welding, e.g. by ultrasound welding, with exactly adapted
welding patterns. In this case, the welding seam is the
predetermined breaking line.
The problem with predetermined breaking lines of this kind, which
break open automatically under the pressure from the airbag, is
that, as a result of manufacturing tolerances, it is extremely
difficult to accurately adjust the required target pressure at
which the predetermined breaking line breaks open.
SUMMARY OF THE INVENTION
The object of the present invention is consequently to propose
another device for the targeted deflation of a gas bag.
According to the present invention, this object is achieved with a
device for deflating a gas bag, in particular an airbag, wherein
said gas bag comprises at least one deflation opening, which is
sealed at a breakable, predetermined breaking line, and wherein
said predetermined breaking line comprises a closure element, which
can be broken open by allowing said closure element to melt or
sublime.
By contrast with the previously known devices, the device according
to the present invention is released actively by the melting or
burning of the closure element, and the predetermined breaking line
is broken open. This means that the breaking open of the
predetermined breaking line can be controlled accurately at any
given time. The deflation device can, for example, be released by
an airbag control module, after a sensor device has detected an
inflation volume of the airbag adequate for the absorption of the
energy released.
A further advantage of the device according to the invention is in
the separation of the release function (melting or burning said
closure element) and the breaking open function of the
predetermined breaking line. Accordingly, the predetermined
breaking line can be optimized to break open rapidly without
expenditure of force and without impairing too extensively the
mechanical strength of the predetermined breaking line in the
closed condition of the deflation opening. In fact, on the one
hand, the predetermined breaking line must break open easily and
without the expenditure of force when the device is released, in
order to release the deflation opening of the airbag within the
shortest possible time. On the other hand, the folded airbag must
be safely sealed in order to guarantee inflation in the event of an
impact. Especially during production of the airbag and installation
into the vehicle, the airbag must withstand deformations and
loading arising in this context, without suffering damage which
could reduce its proper function throughout its required operating
life. The separation of the various functions in the device
according to the invention allows these contradictory demands on
the system to be met.
In a first advantageous embodiment, the predetermined breaking line
comprises a closure seam produced through an appropriate
manufacturing technique in the material of the gas bag, and the
closure element comprises a seam fiber determined by the
manufacturing technique and made from the material the gas bag.
With this embodiment, an electrical element, especially an
electrically conductive heating fiber is associated with the seam
fiber, which heats the seam fiber at at least one position up to a
temperature above the melting temperature of the material of the
gas bag when an electrical current is passed through it. As soon as
the seam fiber is broken through at at least one position, the
closure seam can, if designed appropriately using special weaving
respectively knitting techniques, be opened without the expenditure
of force, thereby releasing the deflation opening.
In a second advantageous embodiment, the predetermined breaking
line comprises a closure seam, and the closure element comprises a
seam fiber made from electrically conductive material. The melting
or sublimation of the closure element can, in this embodiment, be
achieved directly by passing an electrical current through the
closure element.
In a further advantageous embodiment, the predetermined breaking
line comprises a first and second row of closure members, wherein
the closure members of the first row are arranged at a first edge
of the deflation opening of the gas bag, and the closure members of
the second row are arranged in such a manner at a second edge of
the deflation opening of the gas bag that the closure members of
the first row and the closure members of the second row are offset
in the direction of the predetermined breaking line, and wherein
the closure members of the first row and the closure members of the
second row interlock to form a keyed closure in the sealed
condition of the gas bag, as is realized, for example, in the case
of a zip fastener. The predetermined breaking line can, for
example, be designed as a slide-less zip fastener, i.e. as a zip
fastener in which the closure element for producing the keyed
closure, the so-called slide or glide, is removed, wherein the zip
fastener is worked into the deflation opening of the gas bag. In
this case, the closure element preferably comprises an electrically
conductive fiber, which holds together the first and second row of
closure members at at least one position.
It should be noted that the airbag is made from an appropriate
textile material into which the zip fastener can be worked with its
lateral textile strips. The working-in of the zip fastener element
as a closure at the deflation opening of the airbag can be achieved
in this context, for example, by stitching, ultrasound welding or
other fastening techniques.
The zip fastener offers considerable strength transversely to the
direction of opening through the keyed connection of the closure
members, so that an airbag of this kind satisfies the high demands
for handling during installation of the airbag system into the
vehicle, and damage to the installed components can largely be
excluded.
However, in its normal use, a zip fastener can readily be opened in
its longitudinal direction of opening by the so-called slide or
glide, and remains open under slight loading only up to the
position, which has been opened by the slide. If the slide is
removed after closing, the zip fastener can, if it is opened at one
point, be opened unhindered along its entire length as soon as both
ends are pulled apart by separating the keyed connection of the
closure members even with a very slight expenditure of force. With
the opening mechanism described, the separation of the keyed
connection of the closure members is readily achieved and a secure
opening of the deflation opening along the predetermined breaking
line is guaranteed. Since only the keyed connection of the closure
members must be removed, only a very small amount of force is
required for this, and the rate of opening is sufficiently rapid
for the requirements of the system.
At least one of the rows of closure members preferably comprises a
gap, such that the chain formed in the closed condition of the gas
bag by the interlocking closure members is interrupted at one
position and comprises an opening. The opening position of the
closure members may also be formed in that the closure members of
the first row and the closure members of the second row do not
interlock at one position. For example, the initial members of each
of the rows may not be connected with one another, as shown in FIG.
6. It should be noted, that in this context, "chain" is used in the
sense of an "uninterrupted row of similar components". As a result
of the opening in the closure elements connected by keyed
connection, the zip fastener is opened with a small expenditure of
force by the loading from the opening airbag after the melting of
the closure element. This proposal exploits a normally undesirable
property of zip fasteners according to which they fail in the
absence of even a single one or of a few of the keyed closure
elements, and in this context, open without an expenditure of
force.
In both cases, the electrically conductive fiber holds the first
and the second row of closure members together preferably in the
region of the opening. This may, for example, be achieved in that
the closure element encloses the first and second row of closure
members, and, accordingly, in the normal condition prevents the two
rows of closure members from being pulled apart by the pressure
predominating in the gas bag and the keyed connection between the
closure members being removed. Alternatively--and especially in the
case of one embodiment in which at least some of the closure
members of the first and second row are designed in a loop-shaped
manner such that the chain formed in the closed condition of the
gas bag by the interlocking closure members comprises a
longitudinal channel at one position in the interior of the
loop-shaped closure members in the direction of the predetermined
breaking line--the closure element is inserted into the
longitudinal channel, and accordingly prevents the keyed closure
between the two rows of closure members from tearing apart.
It should be noted that the device described above for deflating a
gas bag is particularly suitable for use in a so-called
"intelligent" passenger safety system for a vehicle. A passenger
safety system of this kind comprises in addition to the deflation
device, at least one airbag with a control device 104 and a sensor
device 102 for detecting the relative position of the passenger
relative to the airbag, as shown in FIG. 7. The control device
controls the device for deflating the gas bag on the basis of a
position signal determined by the sensor device at a given position
of the passenger relative to the airbag and releases it. To this
end, the control device evaluates the position signal from the
sensor device, for example, with reference to pressure and/or time,
i.e. with reference to the internal pressure of the airbag
respectively the pressure which the airbag exerts on the passenger
and/or the time during which this pressure acts on the
passenger
In one advantageous embodiment, shown in FIG. 7, the sensor device
comprises at least one sensor 102, which is arranged on the airbag
in a region facing the passenger when the airbag is released. The
sensor may be, for example a force sensor arranged on the airbag,
which responds to the pressure exerted by the airbag on the
passenger and converts this into an appropriate electrical signal.
Such a force sensor is illustrated in FIGS. 8 and 9 and
advantageously comprises at least two electrode structures 200
which are attached at a given distance from one another to the
textile carrier material of the airbag 10 and a layer of
semiconductor material 220, which is attached via the electrode
structures to an active area of the sensor in direct contact with
the electrode structures, whereby the layer of semiconductor
material comprises an internal resistance, which is variable in
dependence upon a deformation of the layer. The textile carrier
material may be any soft textile material. In one variant, which is
particularly advantageous because of its simplicity, the textile
material is the actual material of the airbag, whereby the
electrode structures are attached directly to the airbag.
A sensor of this kind is manufactured without rigid carrier layers,
as is conventional, for example, in currently available foil
pressure sensors. As a result, the sensor comprises a very high
capability for deformation, so that the sensor can readily be
folded together with the airbag. Moreover, any risk of injury to
the passenger resulting from the sensor can largely be excluded
because of the softness of the sensor.
It should be noted, that instead of the force sensor, a capacitive
distance sensor with at least one electrode structure arranged on
the airbag or an inductive distance sensor with at least one
inductive coil arranged on the airbag and supplied with an
alternating voltage may also be used.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of the invention will now be described with
reference to the enclosed figures. The figures are as follows:
FIG. 1: an embodiment with a melting seam as the closure
element
FIG. 2: an embodiment with a zip-fastener closure and melting
wire
FIG. 3: a section through FIG. 2 with a possible arrangement of the
closure element
FIG. 4: an alternative possibility for the arrangement of the
closure element.
FIG. 5 illustrates the opening or gap in one of the rows of closure
members.
FIG. 6 illustrates an alternative embodiment of the two rows of
closure members not interlocking at the end regions of the zip
fastener.
FIG. 7 illustrates a sensor device mounted on an airbag and an
associated control device.
FIGS. 8 and 9 illustrate one embodiment of the present invention in
which the sensor device of FIG. 7 is comprised of at least two
electrode structures which are arranged at a given distance
relative to one another on a textile carrier material and a layer
made from a semiconductor material.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a first embodiment of the present invention. In this
context, FIG. 1 shows a section of an airbag 10, in particular in
the region in which two parts 12 and 14 of the airbag are stitched
together. The two parts 12 and 14 overlap in the region shown and
are normally stitched together with a single seam or a seam of
several rows 16.
To create an appropriate deflation opening 18, the normal seam 16
in the present embodiment is interrupted at a given length L. The
length L of the interruption of the seam 16 corresponds to the
desired length of the deflation opening.
In order to close the airbag, the two parts 12 and 14 of the airbag
are stitched together in the region of the interruption of the
normal seam 16 by means of a sewing thread 20 capable of melting or
sublimation. The melting thread 20 may, for example, comprise a
metal thread the two ends of which are connected to a current
supply 22. When an appropriate electrical current is passed through
the metal thread 20, it is heated up to a temperature above its
melting temperature so that the melting seam is torn open. As soon
as the thread 20 has broken in at least one position, the closure
seam can, with an appropriate design through special weaving
respectively knitting techniques, be opened with out the
expenditure of force thereby releasing the deflation opening
18.
Another embodiment of the device for deflating a gas bag is shown
in FIG. 2. The section of the airbag 10 shown here comprises an
opening 24, in which a suitable zip fastener 26 is attached. The
zip fastener is preferably worked into the airbag material inside
the airbag with its lateral textile strips 27 by means of a
continuous seam 28.
A zip fastener offers a considerable strength transversely to the
direction of opening as a result of the keyed connection of its
closure members 30, so that an airbag fitted with a zip fastener of
this kind satisfies the demanding requirements for handling during
installation of the airbag system into the vehicle, and damage to
the installed parts can largely be excluded.
The zip fastener closure 26 is preferably designed as a slide-less
zip fastener, i.e. as a zip fastener in which the closure element
for production of the keyed connection between the closure members
30, the so-called slide or glider, has been removed. A zip fastener
of this kind can, if it is opened at one position, be opened along
its entire length unhindered with an extremely small expenditure of
force, as soon as the two ends are pulled apart.
To ensure that the zip fastener 26 does not open unintentionally,
at least one closure element 32 capable of melting or sublimation
is associated with the zip fastener, which holds together the two
interlocking rows of closure members 30, for example in at least
one of the end regions 34 of the zip fastener 26. At the opposing
end region, the two rows of closure members can be held together by
an appropriate stitching of the end region to the airbag material
or by any desired end member (not shown), which encloses the two
rows of teeth. Alternatively, a closure element capable of melting
or sublimation may also be attached at this end of the zip
fastener. Independently of the design, the-keyed closure of the two
rows of teeth of the zip fastener is secured under normal
conditions from separation. If the deflation opening is to be
released, the closure element is destroyed by melting or
sublimation, and the security against the separation of the-keyed
closure is removed.
The melting enclosure member 32 shown in FIG. 2 may, for example,
be a melting wire 36, which is looped around the two rows of
closure members 30, and which fixes these in their position
relative to one another (see also FIG. 3). The melting wire is, for
example, passed through the two textile strips 27 of the zip
fastener, so that it only encloses the actual closure elements 30.
This ensures a secure holding of the-keyed connection.
The melting wire is connected by two electrical lines 38 to a
current source, which under the control of the airbag control unit,
supplies the melting wire with an appropriate current, in case the,
airbag has to be stopped in its inflation procedure to avoid injury
to the passenger. The flowing current heats the melting wire to a
temperature above its melting respectively sublimation temperature,
so that the connection created by the melting wire between the two
rows of closure members is broken. As a result of the pressure
predominating in the airbag at this time, the two rows of closure
members are pulled apart at their now free ends, and the zip
fastener opens as described above without substantial expenditure
of force.
An alternative embodiment of the closure element 32 is shown in
FIG. 4. This embodiment may be used, for example, in conjunction
with a zip fastener with closure members 30 designed in a loop
shape. In the case of zip fasteners of this kind, a longitudinal
channel 40 is formed in the interior of the chain formed by the
interlocking closure members 30, into which a melting wire 42 can
be inserted. In this context, the melting wire can be fed through
all or merely through some of the closure members. In the first
case, the electrical supply lines are connected at the two ends of
the zip fastener to the melting wire. In the second case, in which,
for example, the melting wire is merely fed through two adjacent
closure members, the melting wire is preferably passed between the
closure members out of the chain of closure members and connected
to the electrical supply lines at these positions.
It should be noted that the closure element 32 need not be arranged
in one of the end regions of the zip fastener 26. In one
alternative embodiment as shown in FIG. 5, the zip fastener 26 may
comprise an opening 100 at any desired position in the interlocking
rows of teeth, which is then secured by the closure element 32 from
opening. An opening of this kind can, for example, be produced by
cutting out one of the closure elements 30 in one of the two
rows.
* * * * *